The Fast-JX column photolysis model was used at Lancaster University to simulate column profiles of photolysis rates (JO3 and JNO2) centred on the Institute of Atmospheric Physics (IAP) tower site in Beijing for use by the projects under the Atmospheric Pollution & Human Health in a Chinese Megacity (APHH) programme. The photolysis rate profiles are simulated under different aerosol loadings to represent the optical effects of individual species and cloud cover on photochemistry.